1. Field of the Disclosure
Embodiments of the present disclosure generally relate to the field of electronic devices and, more particularly, to applying phase modulation onto millimeter waves with on-off keying (OOK) for spectrum control.
2. Description of the Related Art
Extremely high frequency (EHF) is part of the radio frequency in the electromagnetic spectrum. For example, EHF runs the range of frequencies from 30-300 gigahertz (GHz). Radio waves in this band have wavelengths from one to ten millimeter, giving it the name of millimeter band or millimeter wave. Because of the shorter wavelengths, this band permits the use of smaller antennas than would be required for similar circumstances in the lower frequency bands, to achieve the same high directivity and high gain. High directivity enables a more efficient use of the spectrum for point-to-point communications, interstatellite links, point-to-multipoint communications, etc.
In particular, signals in the 57-64 GHz region are subject to a resonance of the oxygen molecule and are severely attenuated in atmosphere. Therefore, these millimeter bands have an even larger frequency reuse potential and can be widely used in many applications. For example, the 60 GHz band can be used for unlicensed short range (1.7 kilometer) data links. The 60 GHz band can also be used for Wi-Fi standard IEEE 802.11 ad data links with data transfer rates of up to 7 gigabit (Gbit) per second. WirelessHD is another technology that operates near the 60 GHz range. Specifically, the WirelessHD specification is based on a 7 GHz channel in the 60 GHz radio band. Highly directional signal characteristics permit systems in these bands to be engineered in close proximity to one another without causing interference.
However, the regulated bandwidth is limited for this millimeter band in the U.S. and other jurisdictions. For example, the 60 GHz band has an only 7 GHz bandwidth regulated by U.S. Federal Communications Commission (FCC). In addition, the current data transfer rate for the 60 GHz band is less than 4 Gbit per second, which is not high enough for many applications. With a flat frequency spectrum, the bandwidth is not used efficiently. Therefore, there is a need for reducing the effective bandwidth of the frequency spectrum or concentrating the frequency spectrum to the center of the band, and thus increasing the efficiency of the band usage and achieving higher data transfer rates. Although the data rate may be increased by advanced modulation method that increases signal processing complexity to recover the signal, low-complexity transmitter and receiver are always desirable for a product to lower cost, power consumption, maintenance expense, management complexity, integration difficulty, and physical size.